Tuning means for magnetrons



March 13, 1956 Filed April 2, 1951 P. E. DORNEY ET AL TUNING MEANS FOR MAGNETRONS 5 Sheets-Sheet 1 INVENTORS PATRICK E. DORNEY CHARLES R M/h/KRZAK March 13, 1956 Filed April 2, 1951 P, E. DORNEY ET AL TUNING MEANS FOR MAGNETRONS 3 Sheets-Sheet 2 INVENTORS FATE/CK E. DOANEY CHARLES R MAJ/(24K BY I I ATTORN EY March 13, 1956 E. DORNEY ET AL 2,738,441

TUNING MEANS FOR MAGNETRONS Filed April 2, 1951 s Sheets-Sheet 3 INVENTORS PATRICK E DORNE Y CHARLES E MAJ/(RZAK ATTORNEY United States Patent 2,738,441 TUNING MEANS FOR MAGNETRONS Application April 2, 1951, Serial No. 218,804

Claims. (Cl. 315-39.61)

The present invention relates to electron discharge devices, and more particularly to magn'etrons, and is con cerned with improvements in a method and means for tuning magnetrons.

It is a principal object of this invention to provide a simple, dependable and more gradual method of and means for tuning a magnetron through a wide frequency range.

Magnetrons of the type having cavity resonators are well known in the art. Various mechanical means have been proposed to adjust the frequency of oscillation of such magnetrons but these prior devices have limitations. Some tuning means do not permit adjustment over a sufiiciently wide range of frequencies, have too slow tuning rate over part of the range and too rapid tuning rate over the rest of the range, and others include internal bearings and sliding parts which prove to be the source of considerable operating difficulties.

The present invention utilizes the difference in resonant wavelength between a conventional magnetron anode with open cavity ends and the same anode with the cavity ends partially or completely closed on either or both sides. For example, in an unstrappledanode with either symmetrical or rising sun cavities the wavelength with open ends 10) is related to the wavelength with both ends closed (Ml) as follows:

1 1 1 XEZ YW W wherein it is the height of the anode.

This relationship indicates the possibility of a considerable tuning range. Possible useful variations of magnetrons adapted to be tuned by means of the present invention are those which include rising sun anodes with either or both ends completely or partially closed, single strapped anodes with the unstrapped end completely or partially closed and the strapped end open or partially closed, and double strapped anodes with either or both ends partially closed.

In accordance with this invention, the means for partially or completely closing the anode cavity end or ends comprises a resilient tuning member or plate whose outer periphery is positioned against the anode resonator block of the magnetron and which is adapted to be flexed with respect to the magnetron anode and thereby brought into or out of engagement with a progressively larger or smaller portion of an end of the anode.

The mechanical tuning means of the present invention satisfies two major requirements for such devices. It provides for a gradual adjustment and insures good contact between the tuning plate and the anode.

The invention will be more fully understood from the following description of illustrative embodiments thereof taken in conjunction with the accompanying drawing, wherein:

Fig. 1 is a partial longitudinal section showing, schematically, the anode and cathode structure of a magnetron and the tuning means of the present invention;

Fig. 2 is an enlarged, fragmentary, perspective view of the tuning means in relation to the anode;

Fig. 3 is a top view of the tuning plate of Fig. 2, as placed over the end of the anode cavities;

Fig. 4 shows, schematically, various operational positions of the tuning plate;

Fig. 5 shows a top view of a modified form of the tuning plate for a rising sun type anode; and

Fig. 6 is a cross-sectional view taken substantially along line 6-6 of Fig. 5.

Tunable magnetrons adapted to be tuned by the method and means of this invention are well known in the art and their construction per se forms no part of the present invention. In order to limit the description of the specific improvements of our invention, there is disclosed in the drawings a fragmentary showing only of such parts of a magnetron that are necessary for an understanding of the invention. The magnetron, may for instance, be of the general type described in U. S. Patents 2,444,435, or 2,501,196.

Referring now to the drawing, wherein like numerals in the several figures indicate like parts, there is shown an anode structure 19 comprising a cylindrical body 11 and radially disposed vanes 12, this structure being made of a highly conductive material, such as copper. The spaces between the anode vanes provide resonator cavities 13. Cathode element 14 is mounted, in the conventional manner, in the central evacuated discharge space 15. The method and means for causing cathode 14 to emit electrons upon heating are well known in the art.

The novel tuning device is indicated generally by nu meral 16 and comprises a dished annular resilient tuning plate 17, a clamping ring 18 to hold the outer periphery of the plate in position against the anode structure, a flexible diaphragm 19 hermetically sealed to the anode structure at 20, a member 21 hermetically sealed into a central opening of the diaphragm, the inner periphery of the annular tuning plate being engaged with and guided by said member, a control screw 22 adapted to engage a thread provided in member 21, and a worm gear 23 and worm 24 to drive the screw. If desired, the flexible diaphragm 19 may be replaced by a bellows. The tuning plate 17 may be made of any conductive resilient material, such as beryllium-copper or one of the copper-silver alloys. Proper heat treatment and the operating temperature of the magnetron produce and maintain the resiliency of beryllium-copper and copper-silver alloys in a satisfactory manner. 'If preferred, molybdenum may be used for the tuning plate instead of the above compositions. While the outer periphery of tuning plate 17 is flexed toward or away with respect to the anode. The

slits 25 are narrower than the Width of the vanes '12 so as to provide for an overlapping margin whereby variable electrical contact is obtained between the plate and the vanes, see for example the different plate tuning positions illustrated in Fig. 4.

Figs. 5 and 6 show a schematic top view of a rising sun anode structure. In this embodiment, the tuning plate 17:: is slotted to its outer edge as indicated by slots 25a, and overlies the resonant cavities formedby vanes 12a of the anode structure. The outer edges of the tuning plate are clamped to the anode structure by a clamping ring 13a. The ring 18a has an inner configuration corresponding substantially to the end view configuration of the anode wall structure. The configuration of the clamping ring is such as to provide different radial pressure zones about the periphery of the tuning plate and since the plate is slotted radially to the outer edge thereof these different pressure zones cause the plate, during tuning adjustment, to have different rates of anode contact in accordance with the anode configuration.

The tuning device of the present invention operates as follows, the operation of both embodiments shown being substantially identical:

if a change in frequency is desired, worm 24 is rotated whereby worm. gear 23 will drive screw 22, thus causing axial longitudinal displacement, up or down, depending on the direction of rotation of screw 22. The axial displacement of member 21 will, in turn, by engagement or direct connection as indicated at 21a in Fig. 6, depress the inner portion of the annular tuning plate 17, or permit it to rise, as the case may be, thereby flexing the plate and causing it to cover or uncover in contact therewith certain portions of the anode structure, Fig. 4. The member 21 in the embodiment shown in Figs. 1 to 3 may also be connected to the tuning plate 17 by brazing or other means, similarly as indicated at 210 in Fig. 6.

The anode contacting feature of the tuning plate detcrmines the electrical conductive enclosure for the resonators and as the tuning plate is flexed with respect to the vanes of the anode, the electrical contact therewith is varied gradually thus effecting gradual tuning of the magnetron. While it is preferred to have the plate contact the surface of the vanes, in some applications it. may be desirable to merely vary the spacing between the plate and the vanes.

The present arrangement makes it possible to tune conventional magnetrons over a very wide range of frequencies. It involves no sliding or rotating movements in a vacuum but merely the lateral movement of an outer Wall such as the flexible diaphragm of the evacuated envelope. It is thus a simple, accurate and gradual tuning device adaptable to various types of magnetrons.

While the wall structures 12 have been referred to herein as vanes it should be understood that the work vane or vanes is used broadly to include any shaped wall structure that may be employed to define the resonant cavities. For example, the tuning member of this invention may be used in conjunction with resonant cavities of various shapes.

While the invention has been described in connection with some preferred embodiments thereof, it should be clearly understood that the same have been provided for purposes of illustration and that many variations and modifications of the invention may occur to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

I. A tunable electron discharge device of the magnetron type comprising a hollow anode body with a plurality of. radially disposed vanes defining in said body a plurality of open ended cavity resonators, a resilient timing member. disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, an element anchoring said member along the periphery thereof to said body with the outer portion of said member in contact with the outermost portions of the end surfaces of said vanes, and movable means disposed in mechanically coupled relation to said member at a point spaced from the anchored portion thereof to flex said member into more or less contact with the end surfaces of said vanes in accordance with the direction and degree said member is flexed.

.Z. A tunable electron discharge device of the magnetron type comprising a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, a resilient tuning member disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, means anchoring said member to said body adjacent the outer portions of said vanes, and movable means disposed in mechanically coupled relation to said member at a point spaced from the anchored portion thereof to fiex said member with respect to the end surfaces of said vanes, said member being in the form of a plate having a plurality of radial slots therein to enhance flexing movement thereof.

3. A tunable electron discharge device according to claim 2, wherein the plate has the radial slots extending to at least adjacent the periphery thereof.

4. A tunable electron discharge device of the magnetron type comprising a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, a resilient tuning member disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, means anchoring said member to said body adjacent the outer portions of said vanes, and movable means disposed in mechanically coupled relation to said member at a point spaced from the anchored portion thereof to flex said member with respect to the end surfaces of said vanes, said resilient tuning member being in the form of an annular dished plate and said anchoring means includes a clamping ring overlying the peripheral edge portion of said plate and means securing said clamping ring to said anode body.

5. A tunable electron discharge device of the magnetron type comprising a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, a resilient tuning member disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, means anchoring said member to said body adjacent the outer portions of said vanes, movable means disposed in mechanically coupled relation to said member at a point spaced from the anchored portion thereof to flex said member with respect to the end surfaces of said vanes, an envelope enclosing the end of said anode body having said resilient tuning member and means outside of said envelope to actuate said means for flexing said resilient member.

6. A tunable electron discharge device of the magnetron type comprising an anode-vane structure consisting of a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, said anode-vane structure being in the form of the rising sun type of magnetron structure, a resilient tuning member in the form of a plate disposed at one end of said vancs in overlying relation to the end surfaces of said vanes, said plate having radially disposed slots extending to the periphery thereof, a clamping ring disposed in juxtaposed relation to at least adjacent the outer peripheral portion of said plate, the inner periphery of said clamping ring corresponding substantially to the rising sun configuration of said anodevanc structure, whereby the clamping ring exerts pressure on said plate in accordance with the shape of the underlying anode-vane structure and means disposed in mechanically coupled relation with the central portion of said plate to flex said plate with respect to the end surfaces of said vanes.

7. A tunable electron discharge device of the mag netron type comprising an anode-vane structure consisting of a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, said anode-vane structure providing alternately deep and shallow radially disposed cavities, a resilient tuning member disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, said resilient tuning member being generally of plate form with a plurality of radial slots ex tending to at least adjacent the outer peripheral portion thereof, a clamping ring having radially inwardly proplurality "of radially disposed vanes defining in said body a plurality of open ended-cavity resonators, a resilient tuning member disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, said tuning member being of generally-plate form and having radial slots therein smaller in width than the width of said vanes, said slots being disposed in substantial alignment with said vanes so that when the resilient tuning member is flexed into contact with said vanes, the vanes contact the tuning member on both sides of each slot, and means for flexing said tuning member into more or less contact with the end surfaces of said'vanes.

9. A tunable electron discharge device of the magnetron type comprising a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, a resilient tuning member disposed at one end of said vanes in overlying engageable relation to the end surfaces of said vanes, means anchoring said member to said body adjacent the outer portions of said vanes, an envelope enclosing the end of said anode body containing said resilient tuning member, said envelope including a diaphragm and an element carried by said diaphragm axially of said body, said element having a part mechanically coupled to said resilient tuning member at a point spaced radially inwardly from the anchored part of said member, and means disposed outside said envelope for adjusting said element axially of said anode body to flex said member and thereby control the amount of said end surfaces on gaged by said resilient member.

10. A tunable electron discharge device of the magnetron type comprising a hollow anode body with a plurality of radially disposed vanes defining in said body a plurality of open ended cavity resonators, a resilient tuning member disposed at one end of said vanes in overlying relation to the end surfaces of said vanes, said resilient tuning'member being in the form of a plate having its central'portion dished upwardly away from said vanes, said anode body having means to hold the outer peripherial edge portion of said plate adjacent the outer end surfaces of said vanes, and movable means disposed in mechanically coupled relation to said central portion of said plate to flex said plate with respect to the end surfaces of said vanes.

References Cited in the file of this patent UNITED STATES PATENTS 2,293,152 Litton Aug. 18, 1942 2,408,237 Spencer Sept. 24, 1946 2,429,295 Quitter Oct. 21, 1947 2,444,435 Fisk July 6, 1948 2,448,573 Blazier et al. Sept. 7, 1948 2,542,908 Derby Feb. 20, 1951 2,615,156 Smith Oct. 21, 1952 

